Immunocytochemical staining of fresh frozen rhesus monkey retinas was performed using indirect immunofluorescence and immunoperoxidase (avidin-biotin-complex). Affinity-purified antibodies to interphotoreceptor retinoid-binding protein (IRBP) obtained from rabbits was used to localize IRBP on frozen sections. Fresh frozen pineal glands from the same species were stained by the avidin-biotin-peroxidase method. In addition, retinas from rod-dominant and cone-dominant species were examined. Immunocytochemical staining revealed localization of IRBP in the interphotoreceptor space of peripheral equatorial and posterior retina, with marked decrease in staining in the fovea. A transition zone was noted at the ora serrata, where staining was present in the peripheral retina up to the ora serrata, but was absent in ciliary epithelium. Cone-dominant retinas (chick and turtle) showed lack of reactivity to IRBP. Rod-dominant rat retina showed localization of IRBP to the interphotoreceptor space. Primate and rat pineal showed immunocytochemical localization of IRBP. Spontaneously occurring anterior chamber segment anomalies in DBA/2 mice were studied by slit-lamp biomicroscopy and light and transmission electron microscopy (TEM). The opacities consisted of aggregates of basophilic material in the superficial stroma which stained positively for elastin TEM revealed that they were electron dense and extracellular. Iris abnormalities consisted of stromal atrophy and proliferation of corneal endothelium and basement membrane across the iris surface and trabecular meshwork. The corneal opacities seen in DBA/2 mice show a striking similarity to those which characterize familial band-shaped nodular keratopathy, a form of corneal elastosis.